The purpose of this project is to investigate the use of hyperthermia (HT) to deliver/release drugs using liposomal formulations and enhance expression of therapeutic genes in tumors using the HSP70 promoter as a switch. Compelling pre-clinical data for both approaches has led to their clinical evaluation. Specific Aims 1-3 focus on HT and liposomes. The study populations are women with locally advanced breast cancer (LABC) treated with HT+Evacet women with stage IV breast cancer or chest wall recurrences of breast cancer (IV-CW) treated with HT+ Doxil and dogs with soft tissue sarcomas (Can-STS) treated with a novel low temperature sensitive liposome (LTSL)+ HT. Using imaging data, pharmacokinetic analysis microdialysis and tissues biopsies, we will addressing the following specific aims. (1) Evaluate the effects of HT on liposomal uptake in tumor, establish tumor drug concentrations and determine systemic pharmacokinetic parameters. We hypothesize that HT will increase liposomal uptake in tumors and that we can measure burst release of doxorubicin from LTSL during HT and that local HT will not alter systemic pharmacokinetics. (2) MR perfusion imaging will be performed prior to HT to determine whether it can predict tumor liposomal uptake with HT. (3) Extracellular and intracellular pH will be measured prior to treatment to determine if pH is prognostically important for HT and liposomal doxorubicin. Specific Aim 4 is focused on a HT-controlled immunogene therapy approach for feline vaccine associated sarcomas, using the HSP70 promoter to turn on the immunomodulator gene, IL-12. Provocative pre- clinical data suggests that this treatment works supra-additively with radiation therapy. There is enhanced growth delay for primary tumors and an effect on frequency and time to metastasis. In phase I and II studies conducted in Project 2 fractionated radiation therapy will be combined with this gene therapy approach. In this project we will measure systemic and intratumoral levels of IL-12 after intratumoral HT-immunogene therapy administration. We hypothesize that HT will induce production of IL-12 intra-tumorally, that systemic levels of IL-12 will remain low enough that systemic toxicity of IL-12 is not encountered and that the degree of IL-12 expression in tumor will be temperature dependent.